1. Field of the Invention
The present invention relates to towing accessories and more particularly without limitation, to tow bars for connecting a vehicle to be towed to a towing vehicle.
2. Description of the Related Art
A tow bar is generally used for connecting a towing hitch arrangement of a vehicle to be towed, sometimes referred to herein as a towed vehicle, to a towing hitch arrangement of a towing vehicle. For tow bar applications wherein heavy, massive equipment will be moved a relatively short distance, such as where an airliner is to be backed away from a terminal for example, the tow bar generally has only one tow bar leg. For such applications, one end of the tow bar leg may be connected to the front end of the vehicle to be moved and the other end of the tow bar leg connected to the front end of the moving vehicle so the operator of the towing vehicle can face the vehicle to be moved and can carefully observe the response of the towed vehicle as it is being slowly moved by the towing vehicle.
For applications wherein the towed vehicle will be towed at speeds other than very slow speeds, the tow bar generally has two tow bar legs, the front end of each tow bar leg separately and pivotally connected to a head portion of the tow bar. In use, the front ends of the tow bar legs form the apex of an isosceles triangle and the rear ends of the tow bar legs are spaced apart to form the sides of the isosceles triangle. The triangular configuration is intended to cause the towed vehicle to closely track the towing vehicle, both along straightaways and around corners.
Tow bars must generally be designed to accommodate variations in attitude that inherently occur between the towing and towed vehicles, which variations are constantly and continuously changing during use. One such variation in attitude between the vehicles occurs when the instantaneous elevation of the towing vehicle differs from the instantaneous elevation of the towed vehicle. A related variation in attitude between the vehicles occurs when the instantaneous ascent/descent orientation of the towing vehicle differs from the instantaneous ascent/descent orientation of the towed vehicle. Both of these related variations in attitude can be accommodated by apparatus designed to accommodate relative rotations between the towing and towed vehicles about a transverse, horizontal axis, sometimes referred to as the “pitch” axis, see the “z”-axis in FIG. 1.
Another such variation in attitude between the vehicles occurs when the instantaneous horizontal direction in which the towing vehicle is traveling differs from the instantaneous horizontal direction in which the towed vehicle is traveling, such as when the towed vehicle is being pulled around an unbanked corner for example. This situation, sometimes referred to as “yaw”, can be accommodated by apparatus designed to accommodate relative rotations between the towing and towed vehicles about a vertical axis, see the “y”-axis in FIG. 1.
Finally, another such variation in attitude between the vehicles occurs when the instantaneous sidewise tilt of the towing vehicle differs from the instantaneous sidewise tilt of the towed vehicle, such as the rocking motion which occurs when traversing uneven or rough pavement for example. This situation, sometimes referred to as “roll”, can be accommodated by tow bar apparatus designed to accommodate relative rotations between the towing and towed vehicles about a longitudinal, horizontal axis, see the “x”-axis in FIG. 1.
During actual towing operations, all combinations of the pitch, yaw and roll are continuously occurring and constantly changing. Prior art is replete with tow bar designs that have been developed in an attempt to accommodate these phenomena, some of those designs being more successful than others. For example, a ball hitch/ball hitch-receiver combination securing a tow bar to a towing vehicle can theoretically accommodate all three of the pitch, yaw and roll criteria. Although the ability of such a combination to accommodate yaw is acceptable and the pivot axis therefor is well-defined, unfortunately the ability of such a hitch combination to accommodate either pitch or roll is extremely limited. Failure to strictly observe and properly accommodate such pitch and roll limitations can cause disastrous and even fatal consequences.
Another commonly used hitch arrangement involves using a conventional receiver hitch in combination with a conventional square hitch tube. Although such an arrangement may be convenient for connecting a tow bar to a towing vehicle, this type of connection by itself provides absolutely no ability to accommodate any one of the three pitch, yaw or roll criteria. As a result, either the tow bar and/or connections between the tow bar and the towed vehicle must be relied upon to provide a solution for minimizing the potentially detrimental effects arising from pitch, yaw and roll.
Another arrangement that is useful, particularly when towing massive vehicles, such as heavy military equipment for example, comprises a pintle hitch of a towing vehicle connected to a lunette ring hitch. Such a pintle/lunette ring hitch arrangement does provide the ability to accommodate pitch, yaw and roll attitudes between the towing and towed vehicles. Unfortunately, this type of hitch arrangement inherently produces some play, although minimal, between the pintle and the lunette ring. As a result, neither the pitch axis nor the yaw axis are well-defined since the pintle continually shifts back and forth, and forwardly and rearwardly in the opening through the lunette ring. In so doing, the magnitude of the applied towing force is constantly differing between the two tow bar legs causing the towed vehicle to wander or fishtail to a greater extent behind the towing vehicle than it would if the yaw axis between the pintle and lunette ring were well-defined. Such tendency to fishtail exacerbates wear and tear on the towing vehicle, on the towed vehicle, on the pintle, on the lunette ring, and on the pivotal connections between the tow bar legs and the tow bar head, which also visits greater stress on the operator of the towing vehicle while having to contend with such undesirable added activity between the towing and towed vehicles.
What is needed is a tow bar that counteracts the tendency of a towed vehicle to wander or fishtail, which tendency operatively arises from the inherent play between a pintle and lunette ring hitch connection between towing and towed vehicles.
Typically, a tow bar is first connected to a towing vehicle followed by connecting the tow bar to the towed vehicle. It is difficult, if not impossible, to perfectly align a towing vehicle with, and perfectly space the towing vehicle from, a towed vehicle so the tow bar legs can be easily and conveniently connected to the towed vehicle. Many towing hitch arrangements of towed vehicles require precise fore-to-aft, horizontal, and angular alignment of connectors of the two tow bar legs with mating connections of the towing hitch arrangement of the towed vehicle so pivot pins can be inserted horizontally through horizontally-aligned orifices of those mating connections while the tow bar legs are physically held in place relative to the connections of the towed vehicle. Such activity can be extremely stressful, sometimes requiring the efforts of more than one person, such as when connecting massive tow bars used for towing heavy military equipment for example. Such stress and effort could be reduced considerably if each of the tow bar leg connectors could be individually articulated in close proximity to the towed vehicle so each tow bar leg connector could be easily and conveniently mated with the towing hitch arrangement of the towed vehicle while the pivot pins are being inserted.
What is needed is a tow bar wherein the tow bar legs are separately extendable and retractable as needed to accommodate the difference in span of each tow bar leg when connecting the tow bar legs to a towed vehicle hitching arrangement.
What is also needed is a tow bar having articulated tow bar leg connectors for connecting tow bar legs to a towed vehicle hitch arrangement.
In an actual towing operation, it is essential that the spans of the tow bar legs from the tow bar head to the towed hitch arrangement are equal. For tow bar legs which are freely extendable and retractable to simplify connection to the towed vehicle as aforesaid, the spans after making the connections typically are unequal.
What is needed is a tow bar having a locking mechanism which, after connecting to a towed vehicle, separately and automatically locks the tow bar legs wherein the spans of the two bar legs are equal for towing purposes.
Some prior art tow bars are designed to provide a storage capability for the tow bar when the tow bar is not being used. Some of those designs are for tow bars that remain connected to the towed vehicle, such as by pivoting the tow bar legs upwardly at the front end of the towed vehicle and securing the tow bar legs in an upright configuration. Needless to say, that method of storage can be very unsightly and may obstruct forward vision when the towed vehicle is subsequently being driven on its own. Also, this arrangement is not efficient for situations wherein the towing vehicle needs to use that tow bar to pull other towed vehicles.
Accordingly, other prior art tow bars are designed to provide a storage capability wherein the tow bar remains connected to, and stored on, the towing vehicle such as by pivoting the tow bar legs upwardly or sidewise at the rear end of the towing vehicle and securing the tow bar legs in that configuration such as by hooking the tow bar legs to another part of the tow bar. Unfortunately, it is not uncommon for such arrangements to become unhooked, especially when the towing vehicle travels over very rough terrain, such as railroad tracks, potholes, and the like.
What is needed is a tow bar wherein the tow bar legs have self-storing capability and a lock mechanism which automatically locks the tow bar legs in the self-storing configuration.
What is also needed is a locking mechanism which is capable of locking the tow bar legs in either the self storing configuration or an equal-leg-span configuration.
What is further needed is a locking mechanism that is configured to prevent entry of contaminants and debris into internal structure of the locking mechanism.